triumph tiger 1200 de-cat system

Having more power by limiting the weight and reducing the consumptions, is what you can do with the new FreeSpirits kit.

The exhaust system of a motorcycle is very important, but often it is replaced with aftermarket products because of the sound that comes out from the exhaust pipes we decide to assemble… but are we sure that it is a correct choice?

Not all the aftermarket products, in fact, have better performances than the original systems.

Many manufacturers sell inexpensive products that improve the sound of the bike, but the research at the base of the product has not been carried out and, as a result, you may find yourself with a beautiful sound, but with a bike that works much worse than before, warming more, consuming more and maybe even having power emptying or combustion problems that can ruin the engine.

The combustion gases obtained in the combustion cycle, that takes place inside the engine, leave the cylinder with a considerable amount of energy and speed. The original motorcycle’s exhaust system is the result work of a group of specialists who only deal with this component, so it is clear that an economic and untested system, made only for loudness, cannot be improved compared to the original one. First of all, the exhaust system must ensure a drastic reduction of the noise without creating back pressions that generate resistance to the flow of the outgoing gas which then results in a loss of power. If there was no exhaust system the noise at the exit of the cylinder would be deafening and the gas would immediately come out at atmospheric pressure, without having the possibility to flow and cool as it happens in the exhaust pipe.

At the end of the combustion process in the engine, the combustion chamber is full of exhaust gas which must be evacuated to make room for new fresh gas. When the exhaust valve opens, the time needed to make the chamber free is very short, so, if a back pressure to the exhaust limits the escape of the gases, the system will no longer be able to free the chamber in time. Once the valve is closed, a part of the exhaust gases will remain in the combustion chamber and there will be less room for fresh gas, consequently the next combustion will have less air-fuel mixture to burn and therefore we will have less power from the engine.

On the other hand, if well studied, pressure waves can be created in the exhaust to speed up the flow of the outgoing gases, creating consequently a lower pressure inside the chamber than the one of the incoming gas. In this way you would get a similar operation to a vacuum cleaner that sucks the fresh gases and helps to get more fresh gas in less time, creating then a combustion that will generate more power, improving the performance of the engine.

How to understand then if an aftermarket exhaust system improves our bike? And how can we know if it will create problems to our engine?

After a first part of research and development, every quality aftermarket exhaust system passes through the motorcycle bench, where the system is physically mounted on the bike and tested for hours or days, until the best possible result is obtained. The resulting curves are compared with the original ones and you can control both the power curve, where the possible increments at each rotation speed are shown, and the stoichiometry curve, where the ratio between air and gas compared to the optimal ratio is evident.

The system that we are showing in this article presents incredibly improving curves, curves that are very rare to see so clean and linear.

The system in question is the new FreeSpirits de-catalyst kit, created in collaboration with Virex, a well-known company in the motorcycle industry, which makes the “Made in Italy” a symbol of distinction and quality as its strong point.


The first graph shows the performance of the power according to the engine revolutions, we can see how the red curve, obtained from the new exhaust, is improving at every point compared to the blue curve of the original exhaust. The maximum power increases of 6 CV, very difficult to obtain with a exhaust, without adding further changes.

The second graph shows the air-fuel ratio, the dotted horizontal line indicates the ideal line, and we can see how the red line is almost placed on the dotted line, while the blue one is markedly lower.

As for the everyday use we will get a bike that has more power at any number of turns and is more ready when we start to accelerate.

Not just power

The improvements we will get from our new exhaust are not just regarding the most power. A better stoichiometric curve will also lead to a reduction in exhaust gas temperatures and a lower fuel consumption. From the air-fuel curve of the second graph, we note that the higher we climb upwards in the graph, the greater is the amount of air compared to the amount of fuel. We, therefore, succeeded in obtaining an increase in power (graph 1) by reducing the quantity of fuel in favour of a greater quantity of air.

If you are satisfied with what you have seen so far, wait because the improvements are not finished.

The original exhaust systems are produced with low-cheap materials to reduce the price, the FreeSpirits exhaust systems are, conversely, produced with high quality materials, which help the disposal of heat and, at the same time, drastically reduce the weight. The new system weighs only 2.63 kg compared to 4.55kg of the original system, reducing the total weight of the bike by almost 2 kg, an excellent result if you think that there is a reduction of almost 50% of the weight of the drain.

The FreeSpirits exhaust is made with high quality production systems, such as the laser cutting system for the 3-in-1 fitting, or the tapered tube which reduces the diameter of the tube in a progressive and constant way.

Each part has been designed to be able to adapt to the bike, also using the same mounting points as the original systems.


With self-learning service of the control unit it will not be necessary to remap the motorbike, in fact all the results obtained on the bench have been obtained with the original control unit, without remapping and without additional power systems.

Each alteration is totally reversible, as per tradition FreeSpirits and all the pieces are supported by an assembly booklet that integrates many photos.

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